It's possible all this could be leading to some sort of crossover (versus?) between the Avengers and the Guardians of the Galaxy.

IGN spoke with Marvel Studios president and producer Kevin Feige asking about the potential crossover, with Feige remaining coy, but seemingly teasing it might already be happening.

I don’t know. Part of the fun of the comics is that could happen. Any character could interact with any other character because they inhabit the same time period and the same universe. And certainly it is the inclusion of Thanos most specifically that is a declaration to audiences who are paying attention that this is connected to those other universes. Part of the fun is that it could happen someday. I don’t know when that would be. Or maybe I know and I’m not going to tell you!

"Guardians of the Galaxy" has an August 1, 2014 release; "The Avengers: Age Of Ultron" hits May 1, 2015.